Heating and cooling system and method



Oct. 11, 1955 M. w. GARLAND HEATING AND COOLING SYSTEM AND METHOD Filed D80. 8, 1950 INV EN TOR.

M W- GARLAND ATTORNEY United States Patent HEATING AND COOLING SYSTEM AND METHOD .Milton W. Garland, Wayncsboro, Pa., assignor to Fn'ck Company, Waynesboro, Pa., a corporation of Pennsyl- Vania Application December 8, 1950, Serial No. 199,810

*16 Claims. (Cl. 62-3) This invention relates to refrigeration and more particularly to the provision of system adapted for use in the heating and cooling of a fluid product.

The possibilities of employing the heat dissipating element of a refrigeration system for heating a product and subsequently cooling the product by the heat absorbing element of the system have been recognized before. The present invention is concerned with a particular application of such a system by means of which a refrigeration system maybe used in an application for which .it has not heretofore been considered feasible. Although the invention will be described primarily in connection with the processing or pasteurization of milk, its apjplication is notso limited but obviously may be used to process other products.

Practical considerations, particularly the tempera- 'tures which may "be obtained by the heat dissipating and the heat absorbing elements of a given refrigeration system including particular heat absorbing and heat dissipating elements and "employing a particular refrigerant, limit the uses of a conventional compressor condenser evaporator system. In other words the condenser and evaporator temperatures must fall within certain limits for given operating conditions and a given refrigerant. The pasteurization "of milk, in this country at least, is 'controlled by laws which require that it be heated to a "particular temperature and maintained at that temperature for aspecified lengthof time before it is cooled for further handling and storage. Because of the relatively high temperature (in the neighborhood of 180 F.) it has not been found commercially feasible heretofore to employ a refrigeration system for both heating and cooling the milk in the pasteurization process. By employing the device of the present invention, however, the continuous flow heatingand cooling of milk may be obtained and in a commercially feasible and desirable manner.

According it is an object of the present invention to provide a refrigeration system in which the heat dissipat- "ing element is adapted to heat a continuously flowing 'fiuidandin which the heat absorbing element is adapted to coolthe fluid.

A further object of the invention isthe provision of a refrigeration system adapted to commercially produce relatively high condensing temperatures and at which the design operating pressures of conventional compressors are not exceeded.

A further object of the invention is the provision of a regenerative heating and cooling system for particular application "in the pasteurization in the milk.

These and other objects of the invention will become apparent from the accompanying description taken in conjunction with the accompanying drawing in which the sole figure is a diagrammatic lay out of a system embodying applicants invention.

Referring to the drawing a two stage compressor is shown including a lower stage 11 and a higher stage 12. Compressor 11 has a suction line 13 and a discharge line 14. While the invention is not restricted to the use of a particular refrigerant F-114, (C2CI2F4) dichlorotetrafluroethane has been found particularly useful for carrying out the invention. To maintain the superheat of the suction gas in order that condensation does not take place in the compressor discharge head a thermal valve 15 controlled by a bulb 16 is provided in the discharge line 14 of the compressor 11. Bypassing the valve 15 is a heat exchange coil 17 placed in heat exchange relation with the suction line 13 which coil has a supply conduit 18 and discharge conduit 19 for returning the gas passing therethrough back to the discharge line 14 of the compressor.

In normal operation When the suction .gas has the required superheat the discharge from compressor 11 passes directly through the line .14 without going through the heat exchange coil .17. However, if temperature of the suction .gas drops below a predetermined value the valve 15 will "begin to throttle, thus bypassing a portion at least of the discharge from the compressor through "the heat exchange 17 in order to raise the superheat of the suction gas.

From the discharge line '14 the gas enters the suction line 20 of the next higher stage compressor 12. Com- .pressor 12 exhausts through a discharge conduit 21 to a gas cooler 22. The compressors discharge conduit 21 has a temperature responsive valve 23 with a bulb 24 and a heat exchange coil 25 having an inlet 26. and outlet 27, for the same purpose as described in .connection with the compressor 11.

It is apparent therefore that the temperature of the suction gas to each of the compressors 11 and 12 is automatically controlled.

The gas cooler 22 includes a housing having a dis- "tributor plate 30 for the incoming gases which pass over a coil 31 or similar heat exchange means carrying a cooling fluid, preferably water. Flow through the coil 31 is controlled by valve 32 having a bulb 33 responsive to the temperature of the gas near the discharge end of the gas cooler. From the gas cooler 22 the refrigerant normally fiows through conduit 35 to the branch conduit 36 leading to the heat exchanger 33.

Heat exchanger 38 is preferably of the double pipe shell and tube construction or the shell and coil construction. For the purposes of illustration, a double pipe shell and tube is shown including a plurality of sections.

The incoming product enters the heat exchanger through the conduit '40 and is circulated by the pump -41. The liquid enters the tube 42 of the first shell and 'tube and passes through the connecting: tubes in heat exchange relation with liquid which has been previously "heated. For the purposes of illustration this regenerative *first stage takes place in the lower of the shell and tubes shown, the liquid passing through tube 42 which runs through shells 44, 45, 46 and 47 successively and into tube 48.

From the connector tube 48 the warmed liquid is further heated in the condensing section of the heat exchanger in passing through tube 48 which runs through shells 49, 50, 51 and 59 successively and into tube 52. The liquid flows through tube 52 which runs through shells 60 and 61 where further heating may be applied if necessary to further raise or maintain its temperature.

Leaving the last section from the top shell and tube members through the pipe 54 the heated liquid enters the shell 47 of the top shell and tube member of the regenerative section previously referred to and passing down through the section the heated liquid flows through the shell 47, the connector 55, shell 46, connector 56, 'shell 45 'and the connector 57 to the shell 44 from which it discharges by conduit 58 to a cooling system later to be described.

Referring back to the elements of the refrigeration system the compressed gas having left the gas cooler 22 and flown into the conduits 35 and 36 is received in the shell of the shell and tube member 59 where it passes in heat exchange relation with the fluid flowing through the tube thereof and passes subsequently through the shell connectors down through the shell members of the condensing section and flows therefrom as a liquid in the conduit 64. From conduit 64 it flows through valve 65 into the receiver 66.

Branching olf from the line 35 from the gas cooler is a conduit 68 which may conduct the gas through the top section of the shell and tube arrangement for further heating of the liquid flowing through the tubes thereof in the event that such heating should be required. In order to control the flow of the gas through the top section of the shell and tube section a condition responsive valve 69 in conduit 68 has a bulb 70 responsive to the temperature of the liquid product flowing out of the top shell and tube member. Hence, the amount of gas flowing through the top sections is automatically controlled in response to the temperature of the liquid discharging from the last section of the shell and tube heat exchanger.

From the shell 60 the refrigerant passes through the conduit 72 to the accumulator 74. A manually adjustable pressure control valve 73 in the conduit 72 automatically maintains a pressure in the line 72 which will provide the refrigerant temperature desired in the top section of the shell and tube heat exchanger.

While the normal flow of refrigerant from the gas cooler 22 is to the branch line 36 of the condensing section of the heat exchanger, in order to further control the temperature of the product a condition responsive valve 75 is placed in the line 35 which leads to accumulater 76, the valve being responsive to the temperature of the heated liquid leaving the last tube 59 of the condensing section.

In the event that the flow of refrigerant through the gas cooler 22 is greater than that required for the heating of the liquid in the heat exchanger, an auxiliary storage re- 'ceiver 78 is provided which is connected by line 79 to the gas cooler 22. Receiver 78 exhausts through line 80 into the line 64 leading into the receiver 66, suitable valves 81 and 82 being provided for control of the flow through the lines 79 and 80 as desired.

From the receiver 66 liquid refrigerant flows to the accumulator 76 by conduit 83 and to the accumulator 74 by conduit 84. The liquid level in the accumulators .76 and 74 is controlled by conventional float valve structures 85 and 86. From the accumulator 76 the liquid refrigerant passes through liquid line 87 and expansion valve 88 to the evaporator 89 of a relatively high temperature liquid cooler and returns through conduit 90 to the accumulator 76. Similarly liquid refrigerant from the accumulator 74 passes through line 91 and expansion valve 92 to the evaporator 93 of a relatively low temperature liquid cooler and returns in through conduit 94 to the accumulator 7 4. From the accumulator 76 suction line 20 leads to the high stage compressor 12, and accumulator 74 is connected by suction line 13 to the low stage compressor 11.

The heated liquid which has been partially cooled by regeneration in passing through the lower section of the shell and tube heat exchanger flows out the discharge 58 into heat exchange relation with the evaporators 89 and 93 where it is progressively cooled. From the low tem- .perature evaporator 93 the cooled liquid flows out conzduit 96 through the three way valve 97 for normal discharge through conduit 98.

At the beginning of operation, however, in the event that the liquid flowing through the shell and tube heat exchanger fails to reach the required temperature the valve 97 will be automatically positioned so that the liquid flowing therethrough will be recirculated by conduit 99 to conduit 40 through the entire heating and cooling system. Valve 97 is preferably controlled by a bulb 100 responsive to the temperature of the liquid in line 54 leaving the last shell and tube of the heat exchanger, and includes time delay mechanism to permit liquid between the bulb and the valve 97 to pass the valve prior to its changing position.

In the operation of the device, the milk or other liquid to be processed is pumped through the conduit 40, 42, through the tubes of the shell and tube heat exchanger 38 beginning at the lower portion thereof and passing successively through the tubes 44, 45, 46, etc. exiting from the upper shell and tube to the conduit 54 from which it goes through the shell of the shell and tube 47 in heat exchange with the incoming fluid through the first section of the shell and tube members. Thus the incoming liquid is heated by regeneration through the first section; is further heated by heat-exchange with the hot gaseous refrigerant in passing through the condensing section; and if still further heating is required hot refrigerant is circulated through the upper shell and tube members. From the regeneration section the liquid passes over the high and low temperature evaporator members where it is progressively cooled to the desired temperature and flows out to suitable storage receptacles, provided that it has reached the required temperature. If the temperature of the liquid leaving the last heating section is lower than that required, however, the three way valve 97 is automatically positioned to recirculate the cooled liquid through the system until such time as the temperature of the heated liquid reaches the desired level.

The operation of the refrigeration system includes the progressive compression of the suction gases coming from the accumulators 74 and 76, the suction lines having heat exchange means in order to maintain the superheat of the suction gas. From the compressor 12 the refrigerant passes to the gas cooler 22 where its temperature may be slightly lowered if above a predetermined maximum. From the gas cooler the refrigerant normally flows through conduits 35 and 36 into the condensing section of the shell and tube heat exchanger where it is condensed, the liquid refrigerant passing through the tubes of the heat exchanger and to the receiver 66 which feeds the accumulators 74 and 76.

Refrigerant from the gas cooler 22 may be short circuited without being condensed, in such amounts as required, through the valve 75 whose operation is responsive to the temperature of the liquid leaving the condensing section of the heat exchanger. Similarly if the temperature of the liquid leaving the last shell and tube member drops below the desired level, the temperature responsive valve 69 may open sufliciently to permit gaseous refrigerant to flow therethrough, as required, in order to further heat the liquid which has flowed through the condensing section. Excess gaseous refrigerant from the gas cooler 22 may be stored, as required, in the auxiliary storage receiver 78 which is connected to the receiver 66.

Evaporating elements in heat exchange relation with a liquid from the discharge conduit 58 are provided with liquid refrigerant from the accumulators 74 and 76, the

refrigerant returning to the accumulators and to the suction lines of the compressors as described.

It is apparent that the present invention contemplates the provision of a refrigeration system particularly adapted for use with refrigerant for which relatively high condensing temperatures may be obtained without exceeding the design operating pressures of standard compressors, and is particularly adapted to utilize the refrigerant F-l14. The specific use illustrated is for pasteurizing milk and contemplates condensing temperature of approximately F. and cooling temperatures of approximately 34 F. The milk to be pasteurized is circulated through a heat exchanger which consists of a first regenerative heating and cooling section, a second section through, which the product is. passed in heat exchange with the refrigerant to be condensed, and a third section which may further heat the productif desired by passing it in heat exchange with hot refrigerant gas. From the third section the milk is cooled first by the regenerative heating and cooling section with the incoming liquid, and further cooled in first and second heat exchange members by the evaporators of the system.

Whilea refrigeration systemhaving two stage compression, dual condensers, and dual evaporators is shown, the invention'obviouslycontemplates the use of equivalent arrangements of theessential refrigeration elements regardless of their number.

It willbe apparent thatthe invention is not limited to the particular embodiment shown but includes reasonable variations therefrom and equivalents thereof.

What is claimed is:

1. In a refrigeration system having a high side including compressing means and condensing means and a low side including evaporating means and suction means, means for passing a fluid in heat exchange relation with said condensing means, refrigerant by-pass means around said condensing means and to the low side suction means in direct communication with the compressing means, and flow control means in said by-pass means responsive to the temperature of the fluid leaving said heat exchange fluid passing means.

2. The structure of claim 1, and a second heat exchange fluid passing means in series with said first mentioned heat exchange fluid passing means, means for passing uncondensed refrigerant in heat exchange relation with said second heat exchange fluid passing means and returning said refrigerant to the low side suction means, and a second flow control means in said uncondensed refrigerant passing means responsive to the temperature of the fluid leaving said second heat exchange fluid passing means.

3. The structure of claim 1 and regenerative means providing heat exchange between the fluid prior to its entering and leaving said heat exchange fluid passing means.

4. The structure of claim 1, and means for passing the fluid from said heat exchange fluid passing means into heat exchange relation with said evaporating means.

5. The structure of claim 1, and means responsive to the temperature of said suction means for automatically passing the discharge from the compressing means in heat exchange relation with said suction means.

6. The structure of claim 1, and a refrigerant cooler between said compressing means and said condensing means, and means responsive to the temperature of refrigerant leaving said cooler for removing heat from refrigerant passing through said cooler.

7. In a compressor, condenser, evaporator refrigeration system, the compressor having a hot gas discharge conduit and a suction inlet conduit, the means of providing for the desired degree of superheat in the suction gas comprising a valve in said discharge conduit, means responsive to a condition of the suction gas for controlling operation of said valve, and a bypass around said valve and having an end on either side of said valve connected to said discharge conduit intermediate the compressor and condenser, and having its intermediate portion in heat exchange relation with said inlet conduit.

8. The invention defined in claim 7 in which said valve is controlled in response to the temperature of the suction gas.

9. A continuous flow heating and cooling system comprising first, second and third serially connected tube means, first shell means around said first tube means and connected to said third tube means whereby fluid may flow serially through the first to the second and then to the third tube means and then through said first shell means, second shell means around said second tube means, a refrigeration system of the type having interconnected heat dissipating and heat absorbing phases, the: heat dissipating phasev being at least partly embodied in second shell means around said second tube means in order to raise the temperature of fluid flowing through said tube means, liquid refrigerant storage means connected to said second shell means for receiving condensed refrigerant therefrom, said liquid refrigerant storage means being connected to the heat absorbing phase of the refrigeration system, and means for passing fluid from said first shell means in heat exchange relation with saidheat absorbing phase.

10. The system defined in claim 9, third shell means around said third tube means and constituting an auxiliary heat dissipating phase of said refrigeration system.

11; A refrigerating system comprising low andhigh stage serially connected compressors, the low stage compressor discharging to the high stage compressor, first and second condensing means connected in parallel to the high stage compressor discharge, the first condensing means discharging to first and second accumulators, the second condensing means discharging to the second accumulator, first and second evaporators connected respectively to the first and second accumulators, means connecting the inlet of the low stage compressor to the second accumulator, and means connecting the inlet of the high stage compressor to the first accumulator.

12. The invention as defined in claim 11 and conduit means for circulating fluid serially in direct heat exchange relation with said first and second condensing means, said second condensing means having a flow control valve responsive to the temperature of the fluid in said conduit means as it leaves said second condensing: means.

l3. A refrigerating system comprising low and high stage serially connected compressors, the low stage compressor discharging to the high stage compressor, first and second condensing means connected in parallel to the high stage compressor discharge, the first condensing means discharging to first and second accumulators, the second condensing means discharging to the second accumulator, first and second evaporators connected respectively to the first and second accumulators, means connecting the inlet of the low stage compressor to the second accumulator, means connecting the inlet of the high stage compressor to the first accumulator, conduit means for circulating fluid serially in direct heat exchange relation with said first and second condensing means, said second condensing means having a flow control valve responsive to the temperature of the fluid in said conduit means, means for by-passing refrigerant from the high stage compressor to the first accumulator, and control means for said bypassing means responsive to the temperature of fluid in said conduit means as it leaves said first condensing means.

14. In a refrigeration system of the type having interconnected heat dissipating and heat absorbing phases, the heat dissipating phase comprising first and second condensers connected in parallel relationship, valve means in the second condenser for controlling the flow of refrigerant therethrough, first and second series connected heat exchangers mounted in heat exchange relationship with said first and second condensers, respectively, for heating a product flowing through said heat exchangers, and means responsive to the temperature of the product in said second heat exchanger as it leaves said second condenser for controlling the flow of refrigerant through said second condenser.

15. The method of heating and cooling a continuously flowing liquid comprising passing it in heat exchange relation with a first heat dissipating means of a refrigeration system, passing it in heat exchange relation with a second heat exchange means of said refrigeration system, controlling the transfer of heat to the liquid from said second heat exchange means in response to the temperature of said liquid leaving said second heat exchange means, and then cooling the liquid by passing it in heat exchange relation with plural heat absorbing means maintained at successively lower temperatures by said refrigeration system.

16. The method of heating and cooling a continuously flowing liquid comprising regeneratively heating said liquid in a first stage, raising the temperature of said liquid in a second stage by passing it in heat exchange relation with a first condenser of a refrigeration system, further heating said liquid by passing it in heat exchange relation witha second condenser of said refrigeration system, cooling said liquid bypassing it in heat exchange relation with liquid in said first stage, further cooling said liquid by passing it in heat exchange relation with the evaporating element of said refrigeration system and further cooling said liquid by passing it in heat exchange relation with a second evaporator of said refrigerating system at a lower temperature than said first evaporator.

References Cited in the file of this patent UNITED STATES PATENTS Baer Jan. 16, Kucher May 11, Patterson Nov. 17, Damrow July 20, Wildermuth Jan. 1, Goddard June 15, Newton Nov. 16, Bodinus Jan. 24, Grindod June 13, Maseritz Oct. 17, Nussbaum et al. Aug. 14, Ambrose et a1 Nov. 20,

FOREIGN PATENTS Germany Feb. 7, 

